Movie:
Grey Cut-throat Eel, Synaphobranchus affinis

Transcript

Thank you to Dr David Smith for identifying the fish in two movie clips sent to him. He wrote "Both eels appear to be Synaphobranchus; the united gill openings are visible in both specimens. If I had to guess, I would say S. affinis, judging from the position of the dorsal origin. This is a common species that is found all over the world, and that is about the right depth range."